I remember reading an interview with Russell T Davies where he mentioned something about the recording of a
Torchwood: Children of Earth podcast/episode commentary.
I have no idea whether they'll be available to download online or whether they'll stick to what they did with the Series One commentaries - just putting them as a DVD extra on the boxset.
I'm sure that details will be released nearer the time, either on the official BBC website or on websites promoting the DVD release.
However, if you're interested in the making and production of the show, then James Moran (writer of
Day Three of
Torchwood: Children of Earth) has written a great article for the Daily Telegraph about the whole creative process, and how the writers and producers came up with the story.
You can find the article here:
http://www.telegraph.co.uk/culture/t...the-Scene.html